path: root/silx/resources/__init__.py

# coding: utf-8
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# Copyright (c) 2016-2018 European Synchrotron Radiation Facility
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"""Access project's data and documentation files.

All access to data and documentation files MUST be made through the functions
of this modules to ensure access across different distribution schemes:

- Installing from source or from wheel
- Installing package as a zip (through the use of pkg_resources)
- Linux packaging willing to install data files (and doc files) in
  alternative folders. In this case, this file must be patched.
- Frozen fat binary application using silx (frozen with cx_Freeze or py2app).
  This needs special care for the resource files in the setup:

  - With cx_Freeze, add silx/resources to include_files:

    .. code-block:: python

       import silx.resources
       silx_include_files = (os.path.dirname(silx.resources.__file__),
                             os.path.join('silx', 'resources'))
       setup(...
             options={'build_exe': {'include_files': [silx_include_files]}}
             )

  - With py2app, add silx in the packages list of the py2app options:

    .. code-block:: python

       setup(...
             options={'py2app': {'packages': ['silx']}}
             )
"""

__authors__ = ["V.A. Sole", "Thomas Vincent", "J. Kieffer"]
__license__ = "MIT"
__date__ = "08/03/2019"


import os
import sys
import logging
import importlib


logger = logging.getLogger(__name__)


# pkg_resources is useful when this package is stored in a zip
# When pkg_resources is not available, the resources dir defaults to the
# directory containing this module.
try:
    import pkg_resources
except ImportError:
    pkg_resources = None


# For packaging purpose, patch this variable to use an alternative directory
# E.g., replace with _RESOURCES_DIR = '/usr/share/silx/data'
_RESOURCES_DIR = None

# For packaging purpose, patch this variable to use an alternative directory
# E.g., replace with _RESOURCES_DIR = '/usr/share/silx/doc'
# Not in use, uncomment when functionality is needed
# _RESOURCES_DOC_DIR = None

# cx_Freeze frozen support
# See http://cx-freeze.readthedocs.io/en/latest/faq.html#using-data-files
if getattr(sys, 'frozen', False):
    # Running in a frozen application:
    # We expect resources to be located either in a silx/resources/ dir
    # relative to the executable or within this package.
    _dir = os.path.join(os.path.dirname(sys.executable), 'silx', 'resources')
    if os.path.isdir(_dir):
        _RESOURCES_DIR = _dir


class _ResourceDirectory(object):
    """Store a source of resources"""

    def __init__(self, package_name, package_path=None, forced_path=None):
        if forced_path is None:
            if package_path is None:
                if pkg_resources is None:
                    # In this case we have to compute the package path
                    # Else it will not be used
                    module = importlib.import_module(package_name)
                    package_path = os.path.abspath(os.path.dirname(module.__file__))
        self.package_name = package_name
        self.package_path = package_path
        self.forced_path = forced_path


_SILX_DIRECTORY = _ResourceDirectory(
    package_name=__name__,
    package_path=os.path.abspath(os.path.dirname(__file__)),
    forced_path=_RESOURCES_DIR)

_RESOURCE_DIRECTORIES = {}
_RESOURCE_DIRECTORIES["silx"] = _SILX_DIRECTORY


def register_resource_directory(name, package_name, forced_path=None):
    """Register another resource directory to the available list.

    By default only the directory "silx" is available.

    .. versionadded:: 0.6

    :param str name: Name of the resource directory. It is used on the resource
        name to specify the resource directory to use. The resource
        "silx:foo.png" will use the "silx" resource directory.
    :param str package_name: Python name of the package containing resources.
        For example "silx.resources".
    :param str forced_path: Path containing the resources. If specified
        `pkg_resources` nor `package_name` will be used
        For example "silx.resources".
    :raises ValueError: If the resource directory name already exists.
    """
    if name in _RESOURCE_DIRECTORIES:
        raise ValueError("Resource directory name %s already exists" % name)
    resource_directory = _ResourceDirectory(
        package_name=package_name,
        forced_path=forced_path)
    _RESOURCE_DIRECTORIES[name] = resource_directory


def list_dir(resource):
    """List the content of a resource directory.

    Result are not prefixed by the resource name.

    The resource name can be prefixed by the name of a resource directory. For
    example "silx:foo.png" identify the resource "foo.png" from the resource
    directory "silx". See also :func:`register_resource_directory`.

    :param str resource: Name of the resource directory to list
    :return: list of name contained in the directory
    :rtype: List
    """
    resource_directory, resource_name = _get_package_and_resource(resource)

    if resource_directory.forced_path is not None:
        # if set, use this directory
        path = resource_filename(resource)
        return os.listdir(path)
    elif pkg_resources is None:
        # Fallback if pkg_resources is not available
        path = resource_filename(resource)
        return os.listdir(path)
    else:
        # Preferred way to get resources as it supports zipfile package
        package_name = resource_directory.package_name
        return pkg_resources.resource_listdir(package_name, resource_name)


def is_dir(resource):
    """True is the resource is a resource directory.

    The resource name can be prefixed by the name of a resource directory. For
    example "silx:foo.png" identify the resource "foo.png" from the resource
    directory "silx". See also :func:`register_resource_directory`.

    :param str resource: Name of the resource
    :rtype: bool
    """
    path = resource_filename(resource)
    return os.path.isdir(path)


def exists(resource):
    """True is the resource exists.

    :param str resource: Name of the resource
    :rtype: bool
    """
    path = resource_filename(resource)
    return os.path.exists(path)


def _get_package_and_resource(resource, default_directory=None):
    """
    Return the resource directory class and a cleaned resource name without
    prefix.

    :param str: resource: Name of the resource with resource prefix.
    :param str default_directory: If the resource is not prefixed, the resource
        will be searched on this default directory of the silx resource
        directory.
    :rtype: tuple(_ResourceDirectory, str)
    :raises ValueError: If the resource name uses an unregistred resource
        directory name
    """
    if ":" in resource:
        prefix, resource = resource.split(":", 1)
    else:
        prefix = "silx"
        if default_directory is not None:
            resource = os.path.join(default_directory, resource)
    if prefix not in _RESOURCE_DIRECTORIES:
        raise ValueError("Resource '%s' uses an unregistred prefix", resource)
    resource_directory = _RESOURCE_DIRECTORIES[prefix]
    return resource_directory, resource


def resource_filename(resource):
    """Return filename corresponding to resource.

    The existence of the resource is not checked.

    The resource name can be prefixed by the name of a resource directory. For
    example "silx:foo.png" identify the resource "foo.png" from the resource
    directory "silx". See also :func:`register_resource_directory`.

    :param str resource: Resource path relative to resource directory
                         using '/' path separator. It can be either a file or
                         a directory.
    :raises ValueError: If the resource name uses an unregistred resource
        directory name
    :return: Absolute resource path in the file system
    :rtype: str
    """
    return _resource_filename(resource, default_directory=None)


def _resource_filename(resource, default_directory=None):
    """Return filename corresponding to resource.

    The existence of the resource is not checked.

    The resource name can be prefixed by the name of a resource directory. For
    example "silx:foo.png" identify the resource "foo.png" from the resource
    directory "silx". See also :func:`register_resource_directory`.

    :param str resource: Resource path relative to resource directory
                         using '/' path separator. It can be either a file or
                         a directory.
    :param str default_directory: If the resource is not prefixed, the resource
        will be searched on this default directory of the silx resource
        directory. It should only be used internally by silx.
    :return: Absolute resource path in the file system
    :rtype: str
    """
    resource_directory, resource_name = _get_package_and_resource(resource,
                                                                  default_directory=default_directory)

    if resource_directory.forced_path is not None:
        # if set, use this directory
        base_dir = resource_directory.forced_path
        resource_path = os.path.join(base_dir, *resource_name.split('/'))
        return resource_path
    elif pkg_resources is None:
        # Fallback if pkg_resources is not available
        base_dir = resource_directory.package_path
        resource_path = os.path.join(base_dir, *resource_name.split('/'))
        return resource_path
    else:
        # Preferred way to get resources as it supports zipfile package
        package_name = resource_directory.package_name
        return pkg_resources.resource_filename(package_name, resource_name)


# Expose ExternalResources for compatibility (since silx 0.11)
from ..utils.ExternalResources import ExternalResources